INTRODUCTION
The introduction of cutaneous laser resurfacing for the clinical rejuvenation of photodamaged or aging skin, as well as the revision of traumatic scarring, through more precisely controlled remodeling of dermal protein has enabled surgeons in the past decade to greatly increase the variety, effectiveness, and safety of these medical procedures. Most of the prevailing discussion of the mechanism of action behind the two most common clinical lasers in use today, Erbium:Yttrium-Aluminum-Garnet (Er:YAG)(2940nm) and the Carbon Dioxide (CO2)(10,600nm), focuses on the ability of these two lasers to interact primarily with the dermal water chromophores, based in part upon its known infrared absorption spectrum at room and physiologic temperatures (Figure 01). The relative contribution of the direct interaction of these two lasers with dermal protein chromophores remains poorly discussed, if not poorly delineated, as targets for selective photothermolysis.1 The importance of understanding the effectiveness of the protein interaction of these lasers would seem apparent since the primary protein substances, in which the clinician seeks to produce a change, are relatively strong infrared chromophores for the lasers already in clinical use. Additionally, the development of more effective lasers with potentially fewer side effects or non-ablative cutaneous lasers which might produce results similar to currently ablative lasers will center upon the details of this interaction. Finally, explanations for some of the known experimental versus clinical histological effects, i.e., ablation and residual thermal damage depths, for each of these two lasers, are not fully attributable to water acting as the only clinically important chromophore.2 These varying effects may be the result of protein chromophore contributions as yet undefined or the effect of the current specific clinical methods of delivery for each particular type of laser energy.
To determine the validity of dermal proteins, primarily collagen and elastin, as significant chromophores for Er:YAG and CO2 emissions, the primary infrared absorption spectra of proteins within the dermis must be determined apart from the background milieu of cutaneous cellular components, blood and serum proteins, and dermal pigments. An extremely well-suited, unique model for the study of laser effects upon dermal proteins is available through the use of Alloderm (acellular human dermis, LifeCell Corporation) which is provided commercially as a desiccated graft of full-thickness human dermis with a structurally intact basement membrane complex, structurally intact collagen fiber bundles and elastin filaments in typical arrangement and distribution to that found in normal dermis. Retained ground substance proteins have also been demonstrated within the graft.3
This original study will seek to define the absorption spectra of structurally intact human dermal proteins, within the clinically important papillary and reticular dermal layers of acellular human dermis, in an effort to determine if any inherent variation in infrared absorption exists within these dermal layers. This study is also undertaken to determine the presence and magnitude of any differential effects of Er:YAG and CO2 laser energy on dermal proteins, with and without the presence of a water chromophore, using clinical energy levels on desiccated (anhydrous) and rehydrated study samples. Comparative descriptions of any selective energy effects upon collagen or elastin using these two lasers will be determined by light microscopy.
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Rhinoplasty
